feat(ui): stream per-phase progress when installing a preset

[geodro]

Summary

Clicking Add on a preset (elasticvue, phpMyAdmin, mongo, etc.) used to show a single opaque spinner for up to a minute. The biggest contributor to that latency is the first-time image pull, which happened silently inside podman when systemctl --user start lerd-<preset> ran, with no output reaching the UI.

This rewrites the install flow to stream per-phase progress.

Changes

Backend — POST /api/services/presets/{name} now returns application/x-ndjson. A new serviceops.InstallPresetStreaming orchestrator emits a PhaseEvent at every step:

{"phase":"installing_config"}
{"phase":"starting_deps","dep":"elasticsearch","state":"starting"}
{"phase":"starting_deps","dep":"elasticsearch","state":"ready"}
{"phase":"pulling_image","image":"docker.io/cars10/elasticvue:latest"}
{"phase":"pulling_image","message":"Copying blob sha256:... done"}
{"phase":"starting_unit","unit":"lerd-elasticvue"}
{"phase":"waiting_ready","unit":"lerd-elasticvue"}
{"phase":"done","name":"elasticvue","dashboard":"http://localhost:8083"}

The image pull is now explicit and happens before StartUnit, using a new podman.PullImageWithProgress(image, onLine) helper. A small lineWriter splits podman output on both \n and \r so TTY progress-bar rewrites still surface as discrete events.

Frontend — installPreset() consumes the NDJSON stream via ReadableStream, tracks installingPhase / installingMessage / installingDep, and a new presetPhaseLabel(p) helper maps phase → button text ("Pulling image...", "Starting elasticsearch...", "Waiting for ready..."). The modal card shows the live Copying blob ... line underneath the button so a slow registry is distinguishable from a stuck install. Both install entry points (preset modal, service-detail suggestion banner) use the same labels.

Compatibility — CLI (lerd service preset <name>) and MCP (service_preset_install) still call serviceops.InstallPresetByName unchanged; only the HTTP UI response shape is new. macOS is fine: podman.StartUnit already abstracts launchd vs systemctl via UnitLifecycle, and the pull helper just shells out to podman pull.

Notes

publishAfter still wraps the handler, so the eventbus services/status broadcast fires after the stream closes and the WS snapshot refreshes as before.